LS 90 Question

stubby
stubby Posts: 723
edited August 2011 in Vintage Speakers
Hey all, just picked up a pair of pretty nice LS 90s and one of them is showing some strange behavior. The top two midwoofers will occasionally flutter with even a low signal sent to them. They don't bottom out and they don't do it all the time. Any suggestions as to what may be the problem?

I will also have to replace the tweeters as they have some off brand titanium jobbers in them now. Are there replacements available from Polk?

Thanks in advance - looking forward to getting these puppies back into shape!

stubby
SRS 3.1TL
Harman Kardon Citation 5.1
Anthem AVM2



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  • EndersShadow
    EndersShadow Posts: 17,741
    edited August 2011
    stubby wrote: »
    Hey all, just picked up a pair of pretty nice LS 90s and one of them is showing some strange behavior. The top two midwoofers will occasionally flutter with even a low signal sent to them. They don't bottom out and they don't do it all the time. Any suggestions as to what may be the problem?

    I will also have to replace the tweeters as they have some off brand titanium jobbers in them now. Are there replacements available from Polk?

    Thanks in advance - looking forward to getting these puppies back into shape!

    stubby

    If Polk doesn't sell the tweets, I guarantee you someone here has a set.
    "....not everything that can be counted counts, and not everything that counts can be counted." William Bruce Cameron, Informal Sociology: A Casual Introduction to Sociological Thinking (1963)
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  • DollarDave
    DollarDave Posts: 2,575
    edited August 2011
    I've got a driver or two and some tweets that I won't probably use in the near future - if interested, PM me and we can work something out.
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  • ohskigod
    ohskigod Posts: 6,505
    edited August 2011
    switch a good driver with the one that is fluttering. if the problem follows the driver, it is the driver.....if it doesnt. its in the crossover (my guess, as I assume it has aftermarket tweets for a reason.

    I had a pair of those, badass speakers....worth a little effort to get them 100%
    Living Room 2 Channel -
    Wiim Ultra. Jolida CD player. Fiio k11 R2R DAC, XTZ as300 Edge amp. Focal Cobalt 826 towers,

    Upstairs 2 Channel Rig -
    Classe Audio 5 Preamp, DIY1200as2 Icepower Amp x 2, Wiim pro streamer and Topping E70 Velvet DAC, California Audio Labs DX1 CD player, Polk LSi15's with MM840 woofer upgrade.

    Studio Rig - Scarlett 18i20(Gen3) DAW, Schitt Saga 2 preamp, Topping a90 headphone amp, Mac Mini, Audiophonics Hypex NC252m amp, Polk r200's
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  • dorokusai
    dorokusai Posts: 25,576
    edited August 2011
    If it's what I'm thinking of what your describing, they're just old and the driver vc and spider are worn out. They will eventually fail so I'd look for replacements now.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
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  • FTGV
    FTGV Posts: 3,650
    edited August 2011
    stubby wrote: »
    . The top two midwoofers will occasionally flutter with even a low signal sent to them. They don't bottom out and they don't do it all the time. Any suggestions as to what may be the problem?
    First thought would an air leak but if the top drivers share the same volume as the other two they all would exhibit the behaviour.You might try swapping sides with the speaker cables to be sure the problem isnt something source/amp related.
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  • Tony M
    Tony M Posts: 11,861
    edited August 2011
    stubby wrote: »
    Hey all, just picked up a pair of pretty nice LS 90s and one of them is showing some strange behavior. The top two midwoofers will occasionally flutter with even a low signal sent to them. They don't bottom out and they don't do it all the time. Any suggestions as to what may be the problem?

    I will also have to replace the tweeters as they have some off brand titanium jobbers in them now. Are there replacements available from Polk?

    Thanks in advance - looking forward to getting these puppies back into shape!

    stubby
    If you take the bad speakers out, look at that accorian looking disc behind the cone and see if it has come loose from the cone or metal basket. If it has, you can reglue it.:wink:
    Most people just listen to music and watch movies. I EXPERIENCE them.

    “Anger is an acid that can do more harm to the vessel in which it is stored than to anything on which it is poured.”
    --Mark Twain.

    “If at first you don't succeed, then skydiving definitely isn't for you.” - Steven Wright
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  • FTGV
    FTGV Posts: 3,650
    edited August 2011
    I would think if a spider was detached there would be obvious audible side effects with it flopping around.
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  • skrol
    skrol Posts: 3,480
    edited August 2011
    That would be my guess too, detached spider. I've seen it before.
    Stan
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
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  • stubby
    stubby Posts: 723
    edited August 2011
    Took the drivers out and they look OK. Re-installed them and could not duplicate the flutter, but there is a rasping sound coming from them, especially noticed at low sound levels. If you push on the driver slightly, the rasping sound stops for a while. I think the voice coil is on it's last leg.

    Many thanks for all the help, and DaveMuell you have a PM about some spare parts!

    stubby
    SRS 3.1TL
    Harman Kardon Citation 5.1
    Anthem AVM2



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  • stubby
    stubby Posts: 723
    edited August 2011
    As an aside, has anyone considered upgrading the internal wiring on their LS series speaker? I swear it looks like 18 guage out of a Monitor 4. I know size isn't everything but..........

    stubby
    SRS 3.1TL
    Harman Kardon Citation 5.1
    Anthem AVM2



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  • FTGV
    FTGV Posts: 3,650
    edited August 2011
    stubby wrote: »
    Took the drivers out and they look OK. Re-installed them and could not duplicate the flutter, but there is a rasping sound coming from them, especially noticed at low sound levels. If you push on the driver slightly, the rasping sound stops for a while.
    Well since you are actually hearing distortion even at low levels it may be that the spider has separated from the base of the cone.By pushing in the cone you might be momentarily realigning them?
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  • saabracer23
    saabracer23 Posts: 43
    edited August 2011
    I had a woofer with that problem (the audible problem) and I eventually had to buy a new driver.

    Dan
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  • Polkie2009
    Polkie2009 Posts: 3,834
    edited August 2011
    Sometimes you can get a temporary fix to the problem by gently pushing in the driver from the outer edge. It may last for a couple of minutes or a couple of hours,lol, eventually you'll get tired of doing that and just buy some used or new replacement Polk drivers. They are a breeze to replace. Dave's a great guy and will fix you up:)
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  • DollarDave
    DollarDave Posts: 2,575
    edited August 2011
    Polkie2009 wrote: »
    Sometimes you can get a temporary fix to the problem by gently pushing in the driver from the outer edge. It may last for a couple of minutes or a couple of hours,lol, eventually you'll get tired of doing that and just buy some used or new replacement Polk drivers. They are a breeze to replace. Dave's a great guy and will fix you up:)

    I think I jsut figured out why I can't find my surplus drivers - I sold them to you with the 90's, didn't I?
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  • Polkie2009
    Polkie2009 Posts: 3,834
    edited August 2011
    Lol, Dave I thought maybe you had found a couple more somewhere:) Stubby, I need to hang onto these in case I need a backup in the future. Hopefully someone else can chime in with some extras for you. Or you can get new ones through Polk Audio ,tell them you're a CP member and you'll get a discount:)
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  • stubby
    stubby Posts: 723
    edited August 2011
    Polkie2009 wrote: »
    Lol, Dave I thought maybe you had found a couple more somewhere:) Stubby, I need to hang onto these in case I need a backup in the future. Hopefully someone else can chime in with some extras for you. Or you can get new ones through Polk Audio ,tell them you're a CP member and you'll get a discount:)

    No worries, I understand the need for spares. I have seen the tweeters on ebay and Polk is just a call away. Thanks to all for their input.

    stubby
    SRS 3.1TL
    Harman Kardon Citation 5.1
    Anthem AVM2



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